add pre push hook generator script

.maintain/add-prepush-hook.sh

@@ -0,0 +1,49 @@
+#!/bin/sh
+
+# check that rustfmt is installed, or else this hook doesn't make much sense
+command -v rustfmt >/dev/null 2>&1 || { echo >&2 "Rustfmt is required but it's not installed. Aborting."; exit 1; }
+
+# write a whole script to pre-push hook
+# NOTE: it will overwrite pre-push file!
+cat > .git/hooks/pre-push <<'EOF'
+#!/bin/bash -e
+
+echo "Running cargo clippy --fix on project"
+before_clippy=$(git diff --name-only)
+$(command -v cargo) clippy --fix --allow-dirty --allow-staged --all-features
+after_clippy=$(git diff --name-only)
+wait
+
+before_files=()
+while IFS= read -r line; do
+    before_files+=("$line")
+done <<< "$before_clippy"
+
+after_files=()
+while IFS= read -r line; do
+    after_files+=("$line")
+done <<< "$after_clippy"
+
+clippy_modified_files=()
+for i in "${after_files[@]}"; do
+    skip=
+    for j in "${before_files[@]}"; do
+        [[ $i == $j ]] && { skip=1; break; }
+    done
+    [[ -n $skip ]] || clippy_modified_files+=("$i")
+done
+
+# Adds only the files modified by clippy
+if [ ${#clippy_modified_files[@]} -ne 0 ]; then
+    git add "${clippy_modified_files[@]}"
+    echo "Clippy modifications added for: ${clippy_modified_files[*]}"
+else
+    echo "No modifications by clippy"
+fi
+
+echo "Pre-push hook execution completed."
+EOF
+
+chmod +x .git/hooks/pre-push
+
+echo "Hooks updated"